The removal of heavy metal contaminants from soils represents a major contemporary environmental problem. Heavy metal contamination can leave the affected ground unusable for agricultural, residential, commercial or recreational purposes. In addition, the metals can eventually leach into the ground water system and lead to widespread water pollution problems.
A number of soil stabilization methods which leave the offending metals in the soil have been developed. However, only removal of the metal from the soil can provide a permanent solution to heavy metal contamination of soils.
In view of the generally localized nature of metal contamination, it would be useful to develop a method which can be carried out in a compact apparatus which can be mounted in a transportable manner so that the apparatus can be moved to sites which require metal contamination to be removed from the soil. The present invention provides a method which can be carried out in a compact apparatus which can be made transportable and can be moved to sites where heavy metal contamination in the soil must be reduced.
Several methods for removing heavy metal contamination from soil have been described in the paper, Extractive Methods for Soil Decontamination: Operational Treatment Installations in The Netherlands, by J. W. Assink, Dutch Organization for Applied Scientific Research presented at the Second International Conference on New Frontiers on Hazardous Waste Management Proceedings, Sep. 27-30, 1987, Pittsburgh, Pa. The paper describes the processes which are operated in the Netherlands to remove contamination from soil. The article discloses the particular difficulty with removing heavy metal contamination from clay and humus particles. The article discloses that generally, the fine clay particles and humus are separated from the soil and discarded. However, since the fine clay particles and humus particles generally contain a substantial portion of the metal contamination, the safe disposal of the heavy metal contaminated fines and humus can be expensive and difficult.
U.S. patent application Ser. No. 07/930,638 discloses a process for removing heavy metal contamination from soil which disclosure is incorporated herein by reference. The process disclosed in U.S. patent application Ser. No. 07/930,638 can be utilized to leach the heavy metal in the process and apparatus of the present invention.